1. Field of the Invention
This invention relates to a bacterial cell extract prepared from disrupted cells of a microorganism belonging to the genus Mycobacterium, a process for preparing the same, an antitumor preparation containing the same, and an adjuvant preparation containing the same.
2. Description of the Prior Art
It is well known that the tubercle bacilli have a strong antitumor activity, and attempts have been made to administer living cells of the tubercle bacillus to patients with malignant tumor. However, the administration of living cells of the tubercle bacillus involves a great risk of infection and produces severe side effects such as ulceration and fever. For avoiding the risk of infection, a number of attempts have been made to extract the component with antitumor activity from the tubercle bacillus. The active substances so far prepared from the tubercle bacillus include hot-water extract, water-soluble adjuvant, wax, ribonucleic acid, cell wall skeleton, extracted cell residue with organic solvents, and the like.
However, these substances derived from the tubercle bacillus leave much to be improved. The substances having only slight side effects are not always high in antitumor activity, while those having a high antitumor activity tend to produce severe side effects such as hepatic or renal disturbances, fever, vomiting, and ulceration. Moreover, some substances require a complicated procedure for the preparation and the substances thus obtained are not always high in antitumor activity.
The present inventors have performed intensive and extensive studies of various extracts prepared from cells of the tubercle bacilli and related microorganisms, and have found quite unexpectedly that an active substance having a high antitumor activity and low toxicity can reproducibly be prepared with good yield on a simple procedure.